The present invention describes a device and a procedure which are used routinely in the study of macromolecules: i.e. the transfer of electrophoresed species to thin membrane sheets, commonly called blotting.
It is the general object of the present invention to provide an improved method and apparatus to carry out blotting of biological components. The basis of the invention is a novel blotting procedure and apparatus which requires thin, low concentration gels for maximum effectiveness. Such gels are made possible and practical by the horizontal electrophoresis gel tray mold assembly described in a co-pending application Ser. No. 051,761 filed May 20, 1987 by Hurd et al. entitled A METHOD AND APPARATUS FOR MOLDING THIN GEL SLABS HORIZONTALLY WITH INTEGRALLY MOLDED LARGE VOLUME WELL SAMPLES.
The complete disclosure of said '761 application is incorporated herein by this reference to the '761 application.
Blotting is the process by which material such as DNA, RNA, proteins or the like which have been resolved electrophoretically in a gel matrix are transferred to an electrostatically charged membrane sheet in order to be visualized and analyzed.
In conventional prior art blotting procedures, species which have been separated by electrophoresis are transferred to appropriate membranes by driving the species onto the membrane electrophoretically or by drawing them out of the gel by a flow of buffer passing through both gel and membrane (see, for example, Kreisher, J. H., U.S. Pat. No. 4,589,965, 1986, and Southern, E. M. J. Mol. Biol. 98:503, 1975). The use of an electric current or buffer flows is necessitated by the fact that the electrophoretic gels are commonly 5-10 mm thick. In gels of this thickness an independent, active driving force is needed to bring the species of interest through the gel into contact with the blotting membrane.
In the most commonly used procedures, the membranes are layered on top of the gels, and then the gel and membrane together are sandwiched in the blotting apparatus. At this point the fluid or electrical current is initiated to drive the materials out of the gel and onto the membrane. These prior art procedures are time-consuming, often requiring several hours or more to complete. The electrophoretic units require costly power supplies and transfer chambers. Those techniques utilizing fluid flows as the driving force often require 20 hours or more to effect the transfer of the material to the membrane from the gel. In addition, fluid streams require large volumes of buffer in order to effect the transfer.